Accuracy of a stormwater monitoring program for urban landuses

This study examined the accuracy of an urban stormwater monitoring program in estimating the annual discharge load (L_T) and the annual reduction rate by a stormwater treatment device (R_T) for total suspended solids. A calibrated stormwater management modelwas used to generate the entire stormwater runoff events in one year and was used to estimate L_T and R_T under different monitoring strategies having limited numbers of runoffevents, including random, wet season, antecedent dry days (ADD)-based, monthly, and seasonally weighted. For random monitoring, 12 storms were required to estimate the valuesof LT and RT with mean relative errors of 13.98 and 0.24%, respectively. Monthly monitoring had slightly greater mean relative errors compared to random monitoring. Wet season and ADD-based monitoring underor overestimated both L_T and R_T. Monitoring with equal numbers of storms from the wet and dry seasons best estimated LT and RT.